Pin tumbler locks generally feature four primary components: an outer casing, a plug, a locking mechanism and a series of parallel pin stacks. Formed through the casing is a cylindrical bore within which the cylindrical plug is rotatably housed. Opening at the front end of the plug is a slot, or “keyway,” that extends axially into it and is configured to receive a key having a specific cut. At the rear end of the keyway typically is a lever or cam arrangement that actuates the locking mechanism to engage or release the lock upon relative rotation of the plug and casing. Formed within both the casing and plug is a parallel series of aligned holes (typically, four to six, but can be more or less) that open to the keyway and extend radially upward (when the keyway's front opening is vertically oriented) into the casing where their respective upper ends are closed. The plug and casing portions of these aligned holes meet along an imaginary plane line commonly referred to as the “shear line.”
Within each aligned hole is a tumbler pin stack defined by a spring-loaded “driver pin” pressing downward against a sliding “key pin.” When the keyway is empty (i.e., no key is within it) the bottom of each key pin rests along a short flange that juts into the keyway and runs transverse to the pin axis to prevent key pins sliding completely down into the keyway slot. The upper ends of the driver pins abut coil springs that force the driver pins, and therefore the key pins, down toward the keyway.
When no key is filling the keyway, either the driver pin or key pin within each pin stack straddles the shear line and thereby collectively prevent the plug from rotating within the casing. Moreover, because the key pins are not all uniform in length (the driver pins are), when a key that is not cut to operate with the specific lock at hand is inserted into the keyway, one or more of the key pins and/or driver pins will be positioned straddling the shear line. However, when the proper key is inserted, the flat top of each key pin will abut the bottom of its driver pin counterpart precisely at the shear line boundary between the plug and casing. This precise alignment of the pin contact surfaces with the shear line renders the pin stacks ineffective in inhibiting plug rotation so that the locking mechanism can be released by delivering torque to the plug via the key.
in situations in which a pin tumbler lock must be opened, but a properly cut key is not available to the lock owner, the owner or a locksmith will likely be forced to either destroy the lock or employ a lock “picking” or “bumping” technique in order to open a lock. Generally speaking, lock picking involves manipulation of all the existent pin stacks, in one-by-one sequence, until they are all aligned with the shear line so as to permit plug rotation. A variety of devices, ranging from crude took to more sophisticated instruments have been recognized as effective in picking pin tumbler and other types of locks. In contrast, lock bumping is a technique practiced exclusively on pin tumbler locks. Bumping basically involves utilization of a specially cut key to impart to the key pins and, in turn, to the driver pins an impact force that causes each driver pin and key pin pairing to momentarily separate such that all of the driver pins are elevated entirely above the shear line, while all key pins remain entirely below it. Bumping further requires that a rotational force be applied to the plug during that extremely brief moment of pin stack displacement.
That the present inventor is aware, known prior art techniques for opening a pin tumbler type lock without using a key that is cut specifically for it, be it picking techniques or bumping techniques, involve manipulating the pin stacks such that each driver pin ends up being disposed entirely within a lock's outer casing while each key pin is disposed entirely within its plug. Depending on the sophistication of the particular tools used, lock picking can be a tedious proposition simply due to the incremental manner in which each pin stack must be properly aligned with the shear line before the locking mechanism can be released. Lock bumping can also be difficult due to the delicateness and precise timing that may be needed in applying to the key pins an impact force of appropriate magnitude and direction to cause the desired separations of the key pins and driver pins about the shear line while also initiating plug rotation during the fleeting moment in which the pins are so displaced. Consequently, it can be appreciated that there exists a need for a new technique for opening pin tumbler locks that is an alternative to picking and bumping methods and can be performed without any expertise or skill. The present inventor submits that tools disclosed herein enable a user to practice such a technique and further submits that his conceived method for using them on a pin tumbler lock substantially fulfill this outstanding need.